Comment on "Ongoing Adaptive Evolution of ASPM, a Brain Size Determinant in Homo sapiens"

Harvard University, Cambridge, Massachusetts, United States
Science (Impact Factor: 33.61). 05/2007; 316(5823):370. DOI: 10.1126/science.1137568
Source: PubMed


Mekel-Bobrov et al. (Reports, 9 September 2005, p. 1720) suggested that ASPM, a gene associated with microcephaly, underwent natural selection within the last 500 to 14,100 years. Their analyses based
on comparison with computer simulations indicated that ASPM had an unusual pattern of variation. However, when we compare ASPM empirically to a large number of other loci, its variation is not unusual and does not support selection.

Download full-text


Available from: Eric Wang, Mar 03, 2014
  • Source
    • "Human evolution did not stop in the Pleistocene, as is evident, for example, in mutations in enzymes that allow for the digestion of starchy food and dairy products (e.g., Perry et al. 2007), but evolutionary psychologists (e.g., Tooby and Cosmides 1992) contend that the pace of cultural evolution over the last ten thousand years has outstripped that of organic evolution, so that human cognitive adaptations are still to a large extent fi tted to a hunter-gatherer lifestyle. Th ere has been some tentative genetic evidence for ongoing cognitive evolution over the past few thousand years (e.g., P. D. Evans et al. 2005; Mekel-Bobrov et al. 2005), but these fi ndings have faced criticism (Currat et al. 2006; Yu et al. 2007). Th e structure of the human mind constrains and governs human thought and behavior in systematic ways. "

    Full-text · Chapter · Jan 2013
  • Source
    • "This implication led to an interpretation that these genes were also under more recent selection. Later findings, however, suggested that the patterns of polymorphism seen in ASPM and microcephalin, while not expected under neutrality, were not uncommon in the Homo sapiens genome (Currat et al., 2006, Yu et al., 2007). This suggested that demographic effects, rather than selection effects, were primarily responsible for the observed patterns of variation. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The tremendous shifts in the size, structure, and function of the brain during primate evolution are ultimately caused by changes at the genetic level. Understanding what these changes are and how they effect the phenotypic changes observed lies at the heart of understanding evolutionary change. This chapter focuses on understanding the genetic basis of primate brain evolution, considering the substrates and mechanisms through which genetic change occurs. It also discusses the implications that our current understandings and tools have for what we have already discovered and where our studies will head in the future. While genetic and genomic studies have identified many regions undergoing positive selection during primate evolution, the findings are certainly not exhaustive and functional relevance remains to be confirmed. Nevertheless, a strong foundation has been built upon which future studies will emerge.
    Preview · Article · Dec 2012 · Progress in brain research
  • Source
    • "Other authors linked ASPM to more general mechanisms such as ciliary function and spermatogenesis rather than neural development, further confusing the functional significance of ASPM during human evolution [9], [10], [11]. More controversially, a haplotype of ASPM was linked to recent and ongoing selective sweeps among populations of modern humans [12], [13], although these conclusions were subsequently challenged [14], [15] and links between ASPM genetic variants and human intelligence have been refuted [16]. Together, these studies improve our understanding of ASPM function, but do little to resolve why ASPM evinces a purported signature of positive selection in certain primate lineages. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The ASPM (abnormal spindle-like microcephaly associated) gene has been proposed as a major determinant of cerebral cortical size among primates, including humans. Yet the specific functions of ASPM and its connection to human intelligence remain controversial. This debate is limited in part by a taxonomic focus on Old World monkeys and apes. Here we expand the comparative context of ASPM sequence analyses with a study of New World monkeys, a radiation of primates in which enlarged brain size has evolved in parallel in spider monkeys (genus Ateles) and capuchins (genus Cebus). The primate community of Costa Rica is perhaps a model system because it allows for independent pairwise comparisons of smaller- and larger-brained species within two taxonomic families. Accordingly, we analyzed the complete sequence of exon 18 of ASPM in Ateles geoffroyi, Alouatta palliata, Cebus capucinus, and Saimiri oerstedii. As the analysis of multiple species in a genus improves phylogenetic reconstruction, we also analyzed eleven published sequences from other New World monkeys. Our exon-wide, lineage-specific analysis of eleven genera and the ratio of rates of nonsynonymous to synonymous substitutions (d(N)/d(S)) on ASPM revealed no detectable evidence for positive selection in the lineages leading to Ateles or Cebus, as indicated by d(N)/d(S) ratios of <1.0 (0.6502 and 0.4268, respectively). Our results suggest that a multitude of interacting genes have driven the evolution of larger brains among primates, with different genes involved in this process in different encephalized lineages, or at least with evidence for positive selection not readily apparent for the same genes in all lineages. The primate community of Costa Rica may serve as a model system for future studies that aim to elucidate the molecular mechanisms underlying cognitive capacity and cortical size.
    Full-text · Article · Sep 2012 · PLoS ONE
Show more